Control system suitable for automatic coffee makers



Dec. 8, 1953 c, PURPURA 2,662,160

CONTROL SYSTEM SUITABLE FOR AUTOMATIC COFFEE MAKERS Filed Dec. 7, 1949 Q7 J0 J7 Patented Dec. 8, 1953 CONTROL SYSTEM SUITABLE FOR AUTO- MATIGCOFFEE MAKERS August 0. Purpura, Chicago, Ill., assignor to SunbeamCorporation, Chicago, 111., a corporation of Illinois ApplicationDecember 7, 1949, Serial No. 131,581

9 Claims. (01. 219-43) In my prior application, Ser. No. 20,205, filedApr. 10, 1948, now Patent 2,50%,728 for an Automatic Coffee Maker, ofwhich the present application is a continuation-in-part. To illustratethe main features of the present invention, there is disclosed andclaimed a system for automatically brewing coffee and then keeping thecoffee hot until it is to be used.

In my aforesaid application there are two switches and two heatresponsive members to control the switches, both of such members beinginfluenced by the heat of the coffee pot and one of them being alsoheated by an auxiliary heating element.

The primary object of the present invention is to simplify the controlsystem now claimed in the aforesaid application; specific objects beinto eliminate one of the switches and the auxiliary heating means for oneof the heat responsive members.

The objects and advantages of the present invention will more fullyappear from the following detailed description taken in connection withthe accompanying drawing, wherein:

Figure l as a side elevation of a coffee making other, respectively; anda screw 2% serving to utensil embodying the present invention, a portionof the bowl or brewing receptacle being broken away; Fig. 2 is asectionon a larger scale, on line 2-2 of Fig. l; and Fig. 3 is a bottom planView on a still larger scale of the pot, proper, with the dished basemember removed.

In the drawing I have illustrated my invention as applied to aconventional cofiee brewing utensil com rising a pot and a brewing bowl;and for the sake of brevity, the detailed description will be confinedto this particular adaption, although the invention is suitable forother uses.

In the drawing 1 is the coffee pot, proper, surmounted by a brewing bowl2 that has a long conical spout 2 extending down into the pot.

A dish shaped member 3, secured to the under under side of the potbottom are four lugs l,

3, and I0, preferably brazed to the pot; all of the lugs being locatedon a diameter of the pot bottom, with lug i at about the center. A boltll, extending up through base member 3 into lug 7, holds that member tothe pot. Anchored,

at one end to lug 3. and in metallic contact therewith, is a bimetallicbar l2, while a second such bar, M, is anchored at one ens to lug 9;these bars being aligned with each other with their free ends spacedapart from each other. A latch comprising two arms, I5 and i arranged atright an les to each other to form an L, is hung from lug is by a pivotpin ii that is at right angles to the center line of the heat responsivemembers. Arm 5% of the latch is horizontal and overlies the free end ofbar l2; whereas arm i6 is vertical, extending down past the free end ofbar I l and having at its lower end a hook 18. Bar i l has at its freeend a down turned portion is that curves outwardly and downwardly. Theparts are so proportioned that with arm it in the vertical position andthe bar cold, the part it on the bar stands directly above the hook andis latched against downward movement.

Below bar it is a switch. shown as comprising an upper blade 2t and alower blade 2!. These blades are anchored at their middle to lug 9,little blocks of insulating material, 22 and 23, spacing the arms fromthe lug and from each secure the assembly of arms and blocks to the lug.

Current is supplied through a suitable cord (3; wire 25 being connectedto the tail end of switch arm Ell and wire 26 leading to one end of theheating element c. A. short wire 2'! connects the other end of theheating element to the tail of switch arm 2!. Therefore, when the switchis closed, current flows through the heating element, provided that thecord has been plugged into a socket forming part of a distributionsystem.

The free end of switch arm 23 projects beyond the corresponding end ofthe other switch arm and is there provided with a vertically adjustablestop in the form of a screw 28. Bar E4 is provided on its under side,just inwardly from the curved end, with a little button 2d that engagesthe stop 23 when bar it swings down. Bar 52 is also provided with a stopin the form of a screw ill! just below the free end of the horizontalarm of the latch.

Bar I2 is so constructed that its free end swings up as the temperatureof the bar increases. Bar it, on the other hand, does just the opposite,the free end moving or tending to move down with increase intemperature. Therefore bar l2 acts to trip the latch while bar it ,actsto open the normally closed. switch.

With the parts in the positions shown in Fig. 2,

the not being cold, or at least cool, the switch is closed and bar I 4is latched with its free end held clear of the switch. Water having beenplaced in the pot and ground cofiee having been placed in the brewingbowl, the cord may be plugged in and current flow through the heatingelement. As the pot becomes heated, the two heat responsive bars alsobecome hot and the water boils and is forced up into the bowl by thesteam that is generated in the pot. The free end of member 12 starts tomove up and the free end of member M tends to move down. Since the latchrestrains the switch actuating bar from swinging down, stresses arebuilt up in the bar so that, by the time bar [2 has swung upsufiiciently to pull hook it! out from under part [9.

on member hi, there has been stored up'in the latter enough energy todrive the free end of the same down sharply and abruptly open theswitch.

After member l 4 has once been unlatched it cannot swing up intolatching position again until the not has cooled to a predetermined lowtemperature which should be somewhat below the temperature at which thecoffee is to be kept after it has been brewed and flowed back into thepot. The switch closes, however, before this low point in temperature isreached and the bar M latched in its raised position, the temperature ofthe pot rises and member [4 moves down again and opens the switch.Therefore the member 14 in the appended claims to cover all thosechanges and modifications thatfall within the true spirit and scope ofthe present invention.

I claim:

1. In combination, an object to be-heated, an

electrical heating element therefor, a switch to control the flow ofcurrent through said heating element, two heat responsive members ingood heat conductive relation to said object, the first of said membersoperating to open the switch when said object above a predetermined low1 temperature, a latch that tends constantly to move into position torestrain the first heat responsive member against functioning, and thesecond heat responsive member having a part that engages the latch andmoves it into the release position when the temperature of saidobjectreaches a predetermined high value.

2. In combination, an object to be heated, an electrical heating elementtherefor, a switch to control the flow of current through saidheatinelement, two heat responsive members; anchored at corresponding ends ingood heat conductive relation to said object and having their other endsfree and spaced apart from each other, said members flexing in oppositedirections relatively to each other under corresponding temperaturechanges, the first of said members acting directly on the switch to holdit open whenever the temperature of said object is above a predeterminedlow value, unless restrained from doing so, a latch located between thefree ends of said members for engaging the first member and restrainingit from functioning, and the free end of the second heat responsivemember engaging the latch and tripping the same when said object attainsa predetermined high temperature.

3. A combination as set forth in claim 2, wherein the latch is biased toenter into latching relation to the first heat responsive memberwhenever the temperature of said object drops to a predetermined levelbelow said predetermined value.

4. A combination as set forth in claim 3. wherein the first heatresponsive member cannot enter into latched relation with the latch,after unlatching, until said object has become relatively cool.

5. Heating means for a coffee pot comprising an electricalpotheatingelement, a switch to control the flow of current through said element,two heat responsive members in good heat conductive relation to the pot,the first of said members being in position to engage the switch andopen it when the pot is at a temperature somewhat below the boilingpoint of water, a pivoted latch to restrain the first heat responsivemember against functioning, and the second heat responsive member beingin position to trip. the latch when the pot reaches the brewingtemperature.

6. Heating means as set forth in claim 5, wherein the latch and thefirst of the heat responsive members are so calibrated that the lattercannot return into latching relation to the latch until the pot cools toa predetermined point at which the coffee. is no longer hot.

7. In an automatic cofiee maker comprising a pot, an electrical heatingelement for said pot, means for controlling said heating element tocause said pot to attain a predetermined high temperature and thereafterto be maintained at a relatively lower temperature comprising, thecombination of an electrical switch for controlling the fiow of currentthrough saidheating element, a first heat responsive member in good heatconductive relation with said pot, a second heat responsive member ingood heat conductive relation with said pot, means operativelyconnecting said second heat responsive member with said switch, a latchengageable with said second heat responsive member for preventing saidsecond heat responsive member from operating said switch, and means onsaid latch engageable by said first heat responsive member to releasesaid latch upon said pot reaching a predetermined high temperature, saidsecond heat responsive member controlling said switch following releaseof said latch to maintain said pot at a temperature substantially lowerthan said predetermined high temperature.

8. In an automatic coffee maker comprising a. pot, an electrical heatingelement for said pot, means for controlling said heating element tocause said pot to attain a predetermined high temperature and thereafterto be maintained .at a relatively lower temperature comprising. thecombination of an electrical switch for controlling the flow of currentthrough said heating element, a first heat responsive member in goodheat conductive relation with said pot, a second heat responsive memberin good heat conductive relation with said pot, said heat responsivemembers having their longitudinal axes substantially coaxial, meansoperatively connecting said second heat responsive member with saidswitch, a latch engageable with said second heat responsive member forpreventing said second heat responsive member from operating saidswitch, and means on said latch engageable by said first heat responsivemember to release said latch upon said pot reaching a predetermined hightemperature, said second heat responsive member controlling said switchfollowing release of said to maintain said not at a temperaturesubstantially lower than said predetermined high temperature.

9. In an automatic coffee maker comprising a pot, an electrical heatingelement for said pot, means for controlling said heating element tocause said pot to attain a predetermined high temperature and thereafterto be maintained at a relatively lower temperature comprising, thecombination of electrical switch means for controlling the fiow ofcurrent through said heating element, a first heat responsive member ingood heat conductive relationship with said pot, a sec and heatresponsive member in good heat conductive relationship with said pot,means operatively connecting said second heat responsive member withsaid switch means, latch means engageable with said second heatresponsive memher for preventing said second heat responsive member fromoperating said switch means to interrupt the current flowing throughsaid heating 6 element, and means on said latch engageable by first heatresponsive member for operating said latch and releasing said secondheat responsive member to interrupt the current flowing through saidheating element upon said not reaching a predetermined high temperature,said second heat responsive member controlling said switch meansfollowing the attainment of said predetermined high temperature by saidpot to maintain said pot at a temperature substantially lower than saidpredetermined high temperature.

AUGUST C. PURPURA,

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 1,461,878 Harvey July 17, 1923 1,728,785 Claytor Sept. 1'7,1929 1,839,935 Thomas Jan. 5, 1932 2,023,114 Biebel Dec. 3, 19352,262,286 Ireland Nov. 11, 1941 2,281,319 Newell Apr. 28, 1942 2,504,728Purpura Apr. 18, 1950

